Cathode layer

This presentation reports some studies on the materials and catalysis for solid oxide fuel cell (SOFC) in the author s laboratory and tries to offer some thoughts on related problems. The basic materials of SOFC are cathode, electrolyte, and anode materials, which are composed to form the membrane-electrode assembly, which then forms the unit cell for test. The cathode material is most important in the sense that most polarization is within the cathode layer. The electrolyte membrane should be as thin as possible and also posses as high an oxygen-ion conductivity as possible. The anode material should be able to deal with the carbon deposition problem especially when methane is used as the fuel. 

Combustion CVD (CCVD) has also been developed and employed in the deposition of functionally and porosity graded LSM-GDC/LSM-LSC-GDC/LSC-GDC cathodes on a YSZ electrolyte with a NiO-GDC anode also deposited by CCVD. Reasonable performances of 0.48 W/cm2 peak power density and 0.11 Qcm2 electrode RP at 800°C were recorded for the cell [101]. CCVD has also been utilized to deposit anode layers with Sn02 as a sacrificial pore former layer [25] and to deposit an SSC-SDC cathode layer, resulting in a low RP of 0.195 Qcm2 at 600°C at OCV [102],... 

FIGURE 7.3 Schematic representation of the basic steps required in fabricating a vapor-deposited OLED test pixel, (a) anode patterning via lithography, (b) deposition of the organic, and (c) metal cathode layers through shadow masks. 

As an example the electrolyte may be tape-cast or calendered. Flat and dense plates of YSZ having thickness down to 150 /mi are readily fabricated. The anode and cathode materials can then be applied (by a slurry) to the faces of the electrolyte and fired on. Alternatively the anode, electrolyte and cathode layers... 

Figure 22 Bipolar cell for aluminum electrolysis due to Alusuisse [236], The vertical bipolar electrodes consist of 3, an anode layer, a ceramic oxide 4, an intermediate conducting layer 5, a cathode layer, e.g., TiB2. 

Fig. 4.10. (a) The average black spot size as a function of storage time in air for an unencapsulated single layer device with a 4 pm thick metal cathode, (b) The black spot density versus the thickness of the cathode layer [109]. 

Subsequent deployment of the new catalyst in the cathode layer of small-area MEAs first, then large-area MEAs, and finally fuel cell stacks represents the typical series of performance tests to check the practical viability of novel ORR electrocatalyst materials. Figure 3.3.15A shows the experimental cell voltage current density characteristics (compare to Figure 3.3.7) of three dealloyed Pt-M (M = Cu, Co, Ni) nanoparticle ORR cathode electrocatalysts compared to a state-of-the-art pure-Pt catalyst. At current densities above 0.25 A/cm2, the Co- and Ni-containing cathode catalysts perform comparably to the pure-Pt standard catalyst, even though the amount of noble metal inside the catalysts is lower than that of the pure-Pt catalyst by a factor of two to three. The dealloyed Pt-Cu catalyst is even superior to Pt at reduced metal loading. 

Aston Dark Space -1 Cathode Layer Cathode Dark Space Negative Glow... 

The reduction of oxygen to takes place at the interface of the three phase boundary. The mixed cathode which allows both electron and to travel along the surface and bulk extends the interface of the three phase boundary to an active zone for the reduction of O2 to 0 . The extension of the active zone depends on the oxygen diffusion, surface exchange coefficient, the microstructure and porosity of the cathode layer, shown in Fig. 2 (a). ... 

The sample is placed in or on an electrode with a suitable geometry and volatilizes as a result of the high electrode temperature. Electrodes made of graphite and with a beaker form are often used. In the case of refractory matrices anodic evaporation is used and the positive column can be observed, or for very sensitive methods also the cathode layer where the volatilized sample ions are enriched (cathode layer effect). 

The energetically important parts of the discharge (cathode layer, dark space and negative glow) as well as the sample are inside the cathode cavity. The volatilization results from cathodic sputtering and/or thermal evaporation. This depends on the fact whether the whole cathode with its outer and inner wall is subjected to sputtering... 

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